To improve the competitiveness of networks in the future, a new evolution network is now researched for a 3rd-generation partnership project (3GPP) network. FIG. 1 is a schematic structural view of an evolution network system for a 3GPP network. The system includes: an evolved UMTS terrestrial radio access network (E-UTRAN), for implementing all functions related to the wireless feature of the evolution network; a mobility management entity (MME), for mobility management of a control plane, including management of a user context and a mobility state and allocation of temporary user identities; a serving gateway (serving GW) entity, for acting as a user plane anchor point between access networks of the 3GPP network for terminating the E-UTRAN; a packet data network gateway (PDN GW) entity, for acting as a user anchor point between an access network of the 3GPP network and an access network of a non-3GPP network, and an interface for terminating the external PDN; a policy and charging rule function (PCRF) entity, for implementing functions of policy control decision and flow-based charging control; and a home subscriber server (HSS), for storing subscription information of users.
The UMTS terrestrial radio access network (UTRAN) or GSM/EDGE radio access network (GERAN) implements all functions relevant to the wireless feature of the existing UMTS/GPRS network; a serving GPRS supporting node (SGSN) implements functions of route forwarding, mobility management, session management, and user information storage in the GPRS/UMTS network.
IP access networks of the non-3GPP network mainly include access networks defined by non-3GPP network organizations, for example, wireless local area network (WLAN), worldwide interoperability for microwave access (Wimax), and code division multiple access (CDMA) network.
An authentication, authorization, and accounting server (AAA server) mainly implements access authentication, authorization, and accounting for user equipment (UE).
It should be noted that, the schematic structural view of FIG. 1 is not the only schematic structural view of the evolution network system for a 3GPP network. The evolution network of a 3GPP network may have various structures.
One requirement on the evolution network of a 3GPP network is to realize the handover or switching of the UE between a 3GPP network and a non-3GPP network. FIG. 2 is a flow chart of a process that the UE is handed over or switched from a 3GPP network to a non-3GPP network in the prior art. The process includes the following steps.
In Step 201, the UE accesses the 3GPP network through a serving GW and a PDN GW.
In FIG. 2, the mobility management network element (MME) and the serving GW belong to the 3GPP network, a non-3GPP GW belongs to the non-3GPP network, and the PDN GW and HSS/AAA server are common network elements shared by the 3GPP network and the non-3GPP network.
In Step 202, the UE triggers the handover or switching from the 3GPP network to the non-3GPP network.
In Step 203, the UE sends an Access Request message to the non-3GPP GW, and requests to access the non-3GPP GW.
As for a WLAN system, the non-3GPP GW in this step is an evolved packet data gateway (EPDG); as for a Wimax system, the non-3GPP GW in this step is an access service network gateway (ASN GW); and as for a CDMA system, the non-3GPP GW is an access gateway (AGW).
In Step 204, an access authentication process is performed between the UE, the non-3GPP GW, and the HSS/AAA server, and the non-3GPP GW obtains the PDN GW address information used by the UE.
In Step 205a, the non-3GPP GW sends a proxy binding update message to the PDN GW.
In this step, it is assumed that an interface protocol between the non-3GPP GW and the PDN GW is the proxy mobile internet protocol (PMIP). If an interface protocol between the UE and the PDN GW is the client mobile internet protocol (CMIP), Step 205a is replaced by Step 205b, in which the UE sends a binding update message to the PDN GW. In Step 206a, the PDN GW sends a proxy binding acknowledgement message to the non-3GPP GW.
In this step, it is assumed that the interface protocol between the non-3GPP GW and the PDN GW is the PMIP. If the interface protocol between the UE and the PDN GW is the CMIP, Step 206a is replaced by Step 206b, in which the PDN GW sends a binding Ack message to the UE.
In Step 207, the non-3GPP GW returns an access accept message to the UE.
In Step 208, the PDN GW sends a delete bearer request message to the serving GW, and the serving GW sends the delete bearer request message to the MME.
In Step 209, the MME deletes bearer resources related to the UE, returns a delete bearer response message to the serving GW, and the serving GW returns the delete bearer response message to the PDN GW.
The above flow is a specific example of the process that the UE is handed over or switched from a 3GPP network to a non-3GPP network. Certainly, the handover or change process is not limited to the above descriptions. A 3GPP network involved in the handover or change may be GERAN, UTRAN, or EUTRAN. A non-3GPP network involved in the handover or change may be WLAN, Wimax, or CDMA system.
Once the UE accesses a 3GPP network, the 3GPP network creates bearer resources of the UE and a mobility management context of the UE. The mobility management context of the UE exists in the MME. Furthermore, bearer resources of a 3GPP network and a mobility management context of a 3GPP network are also created in the UE. Therefore, when the UE is handed over or switched from a 3GPP network to a non-3GPP network, user detachment needs to be performed to save network resources. The user detachment includes detachment of the 3GPP network and detachment of the UE. The detachment of the 3GPP network indicates that the 3GPP network deletes the bearer resources of the UE and the mobility management context of the UE, and the detachment of the UE indicates that the UE deletes the bearer resources of the 3GPP network and the mobility management context of the 3GPP network. Here, the mobility management context of the UE exists in the MME.
However, in the process shown in FIG. 2, when the UE is handed over or switched from a 3GPP network to a non-3GPP network, the 3GPP network merely deletes the bearer resources of the UE, but does not delete the mobility management context of the UE, and meanwhile, the UE does not delete the bearer resources and mobility management context of the 3GPP network as well.
As known from the above that, the prior art neither provides a method for 3GPP network detachment when the UE is handed over or switched from a 3GPP network to a non-3GPP network, nor provides a specific method for user detachment of the UE when the UE is handed over or switched from a 3GPP network to a non-3GPP network. That is to say, no specific solution for user detachment when handover or change occurs in a heterogeneous network is provided in the prior art.
In addition, if the UE has a single radio capability, that is, the UE can access only one network, after the UE is handed over or switched from a 3GPP network to a non-3GPP network, user detachment needs to be performed, that is, the 3GPP network needs to detach the UE, and the UE needs to be detached from the 3GPP network. The detaching, by the 3GPP network, the UE includes that the 3GPP network deletes the bearer resources of the UE on the 3GPP network side, and the mobility management context of the UE in the MME. The detaching, by the UE, from the 3GPP network includes that the UE deletes the bearer resources and mobility management context created when the UE accesses the 3GPP network.
If the UE has a dual radio capability, that is, the UE can access two networks at the same time, after the UE is handed over or switched from a 3GPP network to a non-3GPP network, it is judged whether the 3GPP network needs to detach the UE according to, for example, information of operator policies. In other words, the prior art does not provide a solution for determining whether to perform the user detachment when the UE is handed over or switched from a 3GPP network to a non-3GPP network.
To sum up, during researches and applications, the inventor(s) of the present invention finds that the prior art has at least the following problems: the prior art neither provides a specific solution for user detachment when a handover or change occurs in a heterogeneous network, nor provides a solution for judging whether to perform user detachment when handover or change occurs in a heterogeneous network.